Development of estrogen-related diseases such as osteoporosis, endometriosis, atherosclerosis, and breast cancer is related to "life- style" factors which include diet, reproductive activity, obesity, and exposure to environmental agents. These life-style factors shift the balance of competing estrogen metabolic pathways, the products of which either promote or inhibit the proliferation of estrogen sensitive tissues. We propose a research plan for development of an innovative monoclonal antibody-based immunodiagnostic test for 16.alpha.hydroxyestrone (16alphaOHE1), a key estrogen metabolite which may be an intermediate marker to detect alterations in estrogen metabolism. This urine or plasma- based test will be used to monitor the efficacy of dietary or pharmacological intervention in the treatment and prevention of disease. Future research and clinical testing will lead to identification of specific clinically relevant indications for this test, and to development of tests for the covalent protein adduct of 16alphaOHE1. An aging U.S. population and increasing use of estrogen therapies will lead to an increasing incidence of estrogen-related disease.